struct ListNode*middleNode(struct ListNode* head)
{
	struct ListNode*cur=head;
	int n=0;
	while(cur)
	{
		 n++;
		 cur=cur->next;
	}
	
	for(int i=0;i<n/2;i++)
	{
	    head=head->next;
	}
	return  head;

}
